examples/src/main/java/org/apache/spark/examples/ml/JavaPrefixSpanExample.java
/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *    http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.spark.examples.ml;

// $example on$
import java.util.Arrays;
import java.util.List;

import org.apache.spark.ml.fpm.PrefixSpan;
import org.apache.spark.sql.Dataset;
import org.apache.spark.sql.Row;
import org.apache.spark.sql.RowFactory;
import org.apache.spark.sql.SparkSession;
import org.apache.spark.sql.types.*;
// $example off$

/**
 * An example demonstrating PrefixSpan.
 * Run with
 * <pre>
 * bin/run-example ml.JavaPrefixSpanExample
 * </pre>
 */
public class JavaPrefixSpanExample {
  public static void main(String[] args) {
    SparkSession spark = SparkSession
      .builder()
      .appName("JavaPrefixSpanExample")
      .getOrCreate();

    // $example on$
    List<Row> data = Arrays.asList(
      RowFactory.create(Arrays.asList(Arrays.asList(1, 2), Arrays.asList(3))),
      RowFactory.create(Arrays.asList(Arrays.asList(1), Arrays.asList(3, 2), Arrays.asList(1,2))),
      RowFactory.create(Arrays.asList(Arrays.asList(1, 2), Arrays.asList(5))),
      RowFactory.create(Arrays.asList(Arrays.asList(6)))
    );
    StructType schema = new StructType(new StructField[]{ new StructField(
      "sequence", new ArrayType(new ArrayType(DataTypes.IntegerType, true), true),
      false, Metadata.empty())
    });
    Dataset<Row> sequenceDF = spark.createDataFrame(data, schema);

    PrefixSpan prefixSpan = new PrefixSpan().setMinSupport(0.5).setMaxPatternLength(5);

    // Finding frequent sequential patterns
    prefixSpan.findFrequentSequentialPatterns(sequenceDF).show();
    // $example off$

    spark.stop();
  }
}
